refactor(news): remove unused deleteNewsItemsByExternalIds method

Now that the cron service uses `deleteItemsNotInFeed`, the original
`deleteNewsItemsByExternalIds(externalIds)` method on NewsService has
no callers. Drop it together with its tests.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

apps/app/src/features/news/server/services/news-service.spec.ts

@@ -421,23 +421,6 @@ describe('NewsService', () => {
     });
   });
 
-  describe('deleteNewsItemsByExternalIds', () => {
-    test('should call deleteMany with externalId filter', async () => {
-      mocks.newsItemDeleteMany.mockResolvedValue({ deletedCount: 1 });
-
-      await service.deleteNewsItemsByExternalIds(['ext-001', 'ext-002']);
-
-      expect(mocks.newsItemDeleteMany).toHaveBeenCalledWith({
-        externalId: { $in: ['ext-001', 'ext-002'] },
-      });
-    });
-
-    test('should do nothing if externalIds is empty', async () => {
-      await service.deleteNewsItemsByExternalIds([]);
-      expect(mocks.newsItemDeleteMany).not.toHaveBeenCalled();
-    });
-  });
-
   describe('deleteItemsNotInFeed', () => {
     test('should call deleteMany with $nin filter for items not in feed', async () => {
       mocks.newsItemDeleteMany.mockResolvedValue({ deletedCount: 1 });

apps/app/src/features/news/server/services/news-service.ts

@@ -170,15 +170,6 @@ export class NewsService {
     );
   }
 
-  /**
-   * Delete news items that are no longer in the feed
-   */
-  async deleteNewsItemsByExternalIds(externalIds: string[]): Promise<void> {
-    if (externalIds.length === 0) return;
-
-    await NewsItem.deleteMany({ externalId: { $in: externalIds } });
-  }
-
   /**
    * Delete every cached news item whose externalId is NOT in the supplied set.
    * Caller passes the full list of externalIds present in the latest feed; any DB